Hi there, I need some good advice here. I have a 88 Iroc, fresh GM crate 305 that is TPI. I want to upgrade its power to a good amout while still retaining good street quality and ability to drive it long distances. This is NOT my daily driver but I would like to put some power down while still having good gas milage as long as I stay out of the throttle. Would love to still be able to take it on 150-200 mile trips in the summer. What cam does everyone recomend? How about a cheap set of headers? Oh yeah, I have no smog emmisions to worry about, thats all been removed by previous owner. I have a 2500 rpm tci torque converter to put in and shift kit. What about converting from TPI to speed density? any benefits there? How about underdrive pulleys? do they make a good difference? Has stock electronics as well so far.

 

I have an 87, all my mods ive done are in my sig. any questions ask away.
All I know with speed density, they dont take too well to mods.

 

see sig.

 

try a lt4 hotcam and aluminum l98 heads with 1.6 roller rockers and a properly tuned chip with free flowing exhaust, it will open up tons of power yet still pull decent gas milage and be a fun car to cruise around in or take on a road trip.

 

headers make a big difference. I went with edelbrock shorties (50 state legal) but any good pair of shorties and y pipe would be great.

Id stay with MAF.

That torque convertor is really going to help.


Do you really want to keep tpi or go HSR? Either has its advantages. As much as i love tpi i think it would definitely be worth it to go with the HSR. You dont lose too much down low and the gains up top is going to be huge.

If you want to stay with tpi aftermarket runners and port work would be a good idea.

Either way hope you enjoy your car.

 

see my sig as well. 13.70 @ 100.5 with a 2.1 60ft isnt too bad for a 305 is it?

 

thank you all for your input and advise, I cant wait to start ordering some parts and doing some porting work unitl i get enough for a HSR

 

2.1 60ft isn't bad but I like my 1.885 better

 

a 2.1 60ft sucks unless you are in a turd that cant go any faster than that while dead hooking. I'm saying that even with a crappy 60ft time my 305 went 13.70. usually 1 tenth in the first 60ft equals 2 tenths at the end of the quarter so you do the math. I've got the trap speed to go way quicker, if I cut a 1.8 60ft time like I should, that should put me at a 13.30. My point is that you can make a 305 run good pretty easy, heck I dont have a roller cam like you 87 and later guys, and I am running the stock chip! Just trying to be an encouragement to the other 305 guys out there.

 

I would not put an HSR on a 305. The TPI flows enough even for a fairly healthy 305. Besides the TPI helps add torque that a 305 lacks because it is small. Talk to Zepher about it, he did the swap and frankly his 305 is not that strong, but he would probably tell you that. I dont think he is going for a max effot 305, but for the money he spent on the HSR he could have gotten better heads that would have helped his power a lot more. He may be planning on using the HSR on a larger engine in the future which is cool. But if you plan on keeping a 305 and you want to get bang for your buck, stay with the TPI stuff, it really is plenty for at least up to a 300hp 305.

 

thank you again for all the input. My motor is really strong right now, less than 5,000 miles on it. My questing is this.... how do I know if I have a roller cam or not? the car is a 88 IROC and the old motor popped, so the guy before me had a shop put in a new GM crate motor. So what cams can I use that would be great for what I want and still get a decent gas milage so i can take the car on trips? thanks

 

Stock, an 88 IROC would have had a roller cam. A replacement TPI engine would probably have a roller cam as well.